A heat exchanger has previously been proposed--see German published patent application DE-AS No. 20 06 759--in which a sidewall or a door formed is of an undulating sheet metal element so that ducts or channels for a cooling fluid are formed thereby, the respective ducts being separated from each other by the undulation in the sheet metal element. Dust-free cooling of the interior of an electronic circuit cabinet, and the elements retained therein is thus possible.
The ducts formed by the undulating sheet metal are not tightly closed with respect to each other, so that air can escape along the folds or pleats thereof. The air ducting or guidance thus is subject to improvement. Such an undulating sheet metal element is difficult to make with high accuracy if the various folds or undulations are bent, one after the other. To make such an undulating element in one stamping operation is very expensive. It is thus practically not possible to make a sheet metal undulating guide for air cooling of circuit elements from one die due to economic constraints.
It has also been proposed to combine a heat exchanger surrounded by a housing, preferably for a dehumidifer system--in which ducts of the heat exchanger are formed by a package of similar plates which are fitted together. The plates have bent-over lateral edges and a transverse edge--see German Utility Model Patent DE-GM No. 1 860 641. The lateral edges of the plates, in the vicinity of the end faces thereof are formed with recesses. Adjacent sequential plates of the package are so set with respect to each other that the lateral recesses of adjacent plates come to lie at different ends of the heat exchanger. This arrangement is a package of plates located within a housing surrounding it at all sides, through which air enters from both sides through the lateral recesses within the plates forming a first heating zone. The open end or face side of the plates then permits the air to reach an evaporater from which it enters the other portion of the housing to be removed again from the lateral recesses into the ducts of the second heat zone, to leave the heat exchanger in dehumidified condition. The very same air stream thus is temperature treated in this heat exchanger. The heat exchanger temperature is entirely surrounded by the housing which makes cleaning and assembly of the plates with the angled-up sidewalls, stacked together, quite difficult.